Commit message: rds: fix an infoleak in rds_inc_info_copy

The last field "flags" of object "minfo" is not initialized.
Copying this object out may leak kernel stack data.
Assign 0 to it to avoid leak.

Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2016-5244
CWE: CWE-200
Vulnerability description: The rds_inc_info_copy function in net/rds/recv.c in the Linux kernel through 4.6.3 does not initialize a certain structure member, which allows remote attackers to obtain sensitive information from kernel stack memory by reading an RDS message.

Project: net
File: recv.c

void rds_recv_incoming(struct rds_connection *conn, __be32 saddr, __be32 daddr,
		       struct rds_incoming *inc, gfp_t gfp)
{
	struct rds_sock *rs = NULL;
	struct sock *sk;
	unsigned long flags;

	inc->i_conn = conn;
	inc->i_rx_jiffies = jiffies;

	rdsdebug("conn %p next %llu inc %p seq %llu len %u sport %u dport %u "
		 "flags 0x%x rx_jiffies %lu\n", conn,
		 (unsigned long long)conn->c_next_rx_seq,
		 inc,
		 (unsigned long long)be64_to_cpu(inc->i_hdr.h_sequence),
		 be32_to_cpu(inc->i_hdr.h_len),
		 be16_to_cpu(inc->i_hdr.h_sport),
		 be16_to_cpu(inc->i_hdr.h_dport),
		 inc->i_hdr.h_flags,
		 inc->i_rx_jiffies);

	/*
	 * Sequence numbers should only increase.  Messages get their
	 * sequence number as they're queued in a sending conn.  They
	 * can be dropped, though, if the sending socket is closed before
	 * they hit the wire.  So sequence numbers can skip forward
	 * under normal operation.  They can also drop back in the conn
	 * failover case as previously sent messages are resent down the
	 * new instance of a conn.  We drop those, otherwise we have
	 * to assume that the next valid seq does not come after a
	 * hole in the fragment stream.
	 *
	 * The headers don't give us a way to realize if fragments of
	 * a message have been dropped.  We assume that frags that arrive
	 * to a flow are part of the current message on the flow that is
	 * being reassembled.  This means that senders can't drop messages
	 * from the sending conn until all their frags are sent.
	 *
	 * XXX we could spend more on the wire to get more robust failure
	 * detection, arguably worth it to avoid data corruption.
	 */
	if (be64_to_cpu(inc->i_hdr.h_sequence) < conn->c_next_rx_seq &&
	    (inc->i_hdr.h_flags & RDS_FLAG_RETRANSMITTED)) {
		rds_stats_inc(s_recv_drop_old_seq);
		goto out;
	}
	conn->c_next_rx_seq = be64_to_cpu(inc->i_hdr.h_sequence) + 1;

	if (rds_sysctl_ping_enable && inc->i_hdr.h_dport == 0) {
		rds_stats_inc(s_recv_ping);
		rds_send_pong(conn, inc->i_hdr.h_sport);
		goto out;
	}

	rs = rds_find_bound(daddr, inc->i_hdr.h_dport);
	if (!rs) {
		rds_stats_inc(s_recv_drop_no_sock);
		goto out;
	}

	/* Process extension headers */
	rds_recv_incoming_exthdrs(inc, rs);

	/* We can be racing with rds_release() which marks the socket dead. */
	sk = rds_rs_to_sk(rs);

	/* serialize with rds_release -> sock_orphan */
	write_lock_irqsave(&rs->rs_recv_lock, flags);
	if (!sock_flag(sk, SOCK_DEAD)) {
		rdsdebug("adding inc %p to rs %p's recv queue\n", inc, rs);
		rds_stats_inc(s_recv_queued);
		rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
				      be32_to_cpu(inc->i_hdr.h_len),
				      inc->i_hdr.h_dport);
		if (sock_flag(sk, SOCK_RCVTSTAMP))
			do_gettimeofday(&inc->i_rx_tstamp);
		rds_inc_addref(inc);
		list_add_tail(&inc->i_item, &rs->rs_recv_queue);
		__rds_wake_sk_sleep(sk);
	} else {
		rds_stats_inc(s_recv_drop_dead_sock);
	}
	write_unlock_irqrestore(&rs->rs_recv_lock, flags);

out:
	if (rs)
		rds_sock_put(rs);
}

Project: net
File: recv.c

int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
		int msg_flags)
{
	struct sock *sk = sock->sk;
	struct rds_sock *rs = rds_sk_to_rs(sk);
	long timeo;
	int ret = 0, nonblock = msg_flags & MSG_DONTWAIT;
	DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
	struct rds_incoming *inc = NULL;

	/* udp_recvmsg()->sock_recvtimeo() gets away without locking too.. */
	timeo = sock_rcvtimeo(sk, nonblock);

	rdsdebug("size %zu flags 0x%x timeo %ld\n", size, msg_flags, timeo);

	if (msg_flags & MSG_OOB)
		goto out;

	while (1) {
		struct iov_iter save;
		/* If there are pending notifications, do those - and nothing else */
		if (!list_empty(&rs->rs_notify_queue)) {
			ret = rds_notify_queue_get(rs, msg);
			break;
		}

		if (rs->rs_cong_notify) {
			ret = rds_notify_cong(rs, msg);
			break;
		}

		if (!rds_next_incoming(rs, &inc)) {
			if (nonblock) {
				ret = -EAGAIN;
				break;
			}

			timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
					(!list_empty(&rs->rs_notify_queue) ||
					 rs->rs_cong_notify ||
					 rds_next_incoming(rs, &inc)), timeo);
			rdsdebug("recvmsg woke inc %p timeo %ld\n", inc,
				 timeo);
			if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
				continue;

			ret = timeo;
			if (ret == 0)
				ret = -ETIMEDOUT;
			break;
		}

		rdsdebug("copying inc %p from %pI4:%u to user\n", inc,
			 &inc->i_conn->c_faddr,
			 ntohs(inc->i_hdr.h_sport));
		save = msg->msg_iter;
		ret = inc->i_conn->c_trans->inc_copy_to_user(inc, &msg->msg_iter);
		if (ret < 0)
			break;

		/*
		 * if the message we just copied isn't at the head of the
		 * recv queue then someone else raced us to return it, try
		 * to get the next message.
		 */
		if (!rds_still_queued(rs, inc, !(msg_flags & MSG_PEEK))) {
			rds_inc_put(inc);
			inc = NULL;
			rds_stats_inc(s_recv_deliver_raced);
			msg->msg_iter = save;
			continue;
		}

		if (ret < be32_to_cpu(inc->i_hdr.h_len)) {
			if (msg_flags & MSG_TRUNC)
				ret = be32_to_cpu(inc->i_hdr.h_len);
			msg->msg_flags |= MSG_TRUNC;
		}

		if (rds_cmsg_recv(inc, msg, rs)) {
			ret = -EFAULT;
			goto out;
		}

		rds_stats_inc(s_recv_delivered);

		if (sin) {
			sin->sin_family = AF_INET;
			sin->sin_port = inc->i_hdr.h_sport;
			sin->sin_addr.s_addr = inc->i_saddr;
			memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
			msg->msg_namelen = sizeof(*sin);
		}
		break;
	}

	if (inc)
		rds_inc_put(inc);

out:
	return ret;
}

Project: net
File: recv.c

void rds_inc_info_copy(struct rds_incoming *inc,
		       struct rds_info_iterator *iter,
		       __be32 saddr, __be32 daddr, int flip)
{
	struct rds_info_message minfo;

	minfo.seq = be64_to_cpu(inc->i_hdr.h_sequence);
	minfo.len = be32_to_cpu(inc->i_hdr.h_len);

	if (flip) {
		minfo.laddr = daddr;
		minfo.faddr = saddr;
		minfo.lport = inc->i_hdr.h_dport;
		minfo.fport = inc->i_hdr.h_sport;
	} else {
		minfo.laddr = saddr;
		minfo.faddr = daddr;
		minfo.lport = inc->i_hdr.h_sport;
		minfo.fport = inc->i_hdr.h_dport;
	}

	minfo.flags = 0;

	rds_info_copy(iter, &minfo, sizeof(minfo));
}

Project: net
File: recv.c

static int rds_cmsg_recv(struct rds_incoming *inc, struct msghdr *msg,
			 struct rds_sock *rs)
{
	int ret = 0;

	if (inc->i_rdma_cookie) {
		ret = put_cmsg(msg, SOL_RDS, RDS_CMSG_RDMA_DEST,
				sizeof(inc->i_rdma_cookie), &inc->i_rdma_cookie);
		if (ret)
			return ret;
	}

	if ((inc->i_rx_tstamp.tv_sec != 0) &&
	    sock_flag(rds_rs_to_sk(rs), SOCK_RCVTSTAMP)) {
		ret = put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMP,
			       sizeof(struct timeval),
			       &inc->i_rx_tstamp);
		if (ret)
			return ret;
	}

	return 0;
}

Project: net
File: recv.c

void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
		  __be32 saddr)
{
	atomic_set(&inc->i_refcount, 1);
	INIT_LIST_HEAD(&inc->i_item);
	inc->i_conn = conn;
	inc->i_saddr = saddr;
	inc->i_rdma_cookie = 0;
	inc->i_rx_tstamp.tv_sec = 0;
	inc->i_rx_tstamp.tv_usec = 0;
}